1. Field of the Invention
The present invention relates generally to detecting leaks in containers that are open to the effects of rain and/or evaporation, and more particularly, to detecting leaks in swimming pools.
2. Discussion of the Prior Art
The accurate measurement of the contents of a sunken tank or an open container at any desired time has presented a problem to the trade, and numerous objections have arisen to the methods heretofore employed for this purpose.
It is well known by swimming pool operators that a pool will suffer a considerable loss of water due to evaporation. It is also well known that the operator of a gasoline filling station suffers annually considerable loss due to leakage and evaporation of the gasoline in the sunken tank. A leaking pool is more likely to happen and very difficult to detect, especially in dry climates.
Several prior art portable fluid level gauges are available. U.S. Pat. No. 1,908,196 to Talbot discloses a portable liquid level gauge which comprises a relatively long metal cylinder having a perforate closure at the bottom and a plug closing the top, the plug having a central aperture and a recess providing a gauge bar seat of non-circular cross section, a gauge bar of non-circular cross section at its base, the base being adapted to be removably received in the seat and the gauge bar having a plurality of faces, each face being marked for a different tank and being adapted to occupy a plurality of angular positions in its seat, a metal float within the cylinder, and a float level indicating rod on the float, the rod passing through the aperture in the plug, and the extremity thereof in association with the markings on one face for the gauge bar to indicate the liquid contents of the tank.
U.S. Pat. No. 2,232,921 to Kuhlman discloses a barrel gauge, comprising a tube, open at both ends, and extending from the upper end of the tube to a point adjacent its lower end is a narrow slot. The calibrated member that is arranged to slide freely through the tube is formed of metal and square or non-circular in cross section. The ends of the rod are plugged to increase its buoyancy. Secured to the lower end portion of the graduated member is a float which may be of cork or other light material held in place on the rod by a one piece resilient gripping member. Formed through the float is an axial opening that is slightly larger in diameter than the tube and the resilient arms bear against the surface of the body of the float surrounding the opening and as the arms tend to flex outwardly or spread apart they engage and grip the float with friction and pressure. The graduated rod being connected to the float will be held in position with its upper portion projecting above the upper end of the tube and the reading of the graduated mark that appears in line with or just above the upper end of the tube will denote the liquid contents within the barrel.
U.S. Pat. No. 3,691,839 to Lasher discloses a portable gauge for measuring the fluid contents of a container having an opening circumscribed by a substantially horizontal wall portion, the gauge having a base adapted to rest on the wall portion, a transparent float extended through the base for free elevational movement with respect thereto, and a scale extended longitudinally of the float adjacent to the base for visual comparison therewith, the scale being calibrated in terms of the volumetric contents of the container at various fluid levels therein.
U.S. Pat. No. 3,983,752 to Holt discloses an oil level gauge for vehicles which have an oil reservoir in a relatively inaccessible location. An upright tube of small diameter has an open lower end below the lowest level of oil in the reservoir, and an upper end which is in a location that is readily viewed by a person checking the oil level. A gauge rod in the tube has a float at its lower end and has a bright colored enlargement at its upper end which is visible through a sight glass in a fitting that surmounts and seals the top of the tube. The float and the enlargement serve to guide the rod.